Sterilization

(FDA) a validated process used to render a product free of all forms of viable microorganisms.(1) (CDC) Sterilization destroys all microorganisms on the surface of an article or in a fluid to prevent disease transmission associated with the use of that item.(2) 

There are a couple forms of sterilization: traditional, liquid chemical, medical sterilization, and ethylene oxide (EO) sterilization. Traditional sterilization often involves “thermal methods, such as steam, to achieve sterilization. Thermal methods have been studied and characterized extensively”. Additionally, “the survival kinetics for gas/vapor/plasma low temperature sterilization methods have also been well characterized.” Liquid chemical sterilization involves two-parts: 

  1. Devices are treated with a liquid chemical germicide (LCG). 

  2. The processed devices are rinsed with water to remove the chemical residues. 

 

 

However, there are limitations for this method. For example, “although the rinse water is treated to minimize any bioburden, it is not sterile. Because the rinse water is not sterile, devices rinsed with this water cannot be assured to be sterile.” Third, medical sterilization which is classified in three categories: plasma gas sterilizers, autoclaves, and vaporized hydrogen peroxide sterilizers.  

  1. Plasma Gas Sterilizers: “…low temperature hydrogen peroxide gas plasma within a chamber to kill all living microorganisms on medical and dental equipment, including bacteria, spores, viruses and fungi. 

  2. Autoclaves: “…a large, steel vessel or chamber that circulates steam at high temperature and pressure to sterilize various items, or as part of an industrial process.” 

  3. Vaporized Hydrogen Peroxide Sterilizers: “…vaporized hydrogen peroxide (VHP) sterilizers also utilize hydrogen peroxide vapor, but plasma gas isn't used within the process. VHP sterilizers remove humidity from an enclosure and hydrogen peroxide vapor is rapidly injected by a generator to reach an effective concentration to sterilize equipment.” 

 

 

Lastly, EO sterilization is sometimes discounted because of the inherent risks. The carcinogenic nature of ethylene oxide (EO) through sterilization emissions has led to the search for alternative sterilization methods and changes to the current EO sterilization method in recent years. However, the search for alternatives remains challenging because of thermodynamic and efficacy issues. The efficacy of EO remains the largest in the US, with over 20 billion devices sterilized each year. However, the issue remains that EO has carcinogenic effects, and for that reason, companies are searching for ways to reduce the concentration of EO used in their sterilization processes to lower their emissions. To date, companies have shown that concentrations at and lower than 300mg/L is lethal enough to kill the Most Resistant Organism (MRO), Bacillus atrophaeus. Changing the EO sterilization concentrations appears to be the most sustainable way to keep this method viable for years to come. Moreover, it will reduce the need for changes to ISO 10993-7, which focuses on residual EO on medical devices. 

Since sterilization includes such a wide range of methods it is used by professionals in almost all medical and laboratory settings. These methods are often applied in cleanrooms and other sterile sectors of hospitals. Meanwhile, autoclaving is a common form of sterilization for lab equipment in research labs. MicroBio consultants work in the certification of cleanrooms and other sterilization techniques for medical devices under FDA and ISO guidance. 

Hospitals and laboratories are the most common places to see sterilization techniques applied. More research is always being conducted to find safer ways to sterilize products with the highest efficacy possible, which could make sterilization techniques more widely applicable. 

Sterilization continues to be developed and changed in accordance with FDA, ISO, and environmental guidelines. The development of these methods will continue to provide the maximum sterility for a wide array of devices. MicroBio Consulting works to study and identify the efficacy of rising forms of sterilization, such as EO sterilization. We also develop cleanrooms and/or certify the efficacy of existing cleanrooms for medical device testing laboratories. Further, work has been done to provide sterilization methods for public operations, such as that used for tattoos.